The semiconductor integrated circuit (IC) industry has experienced exponential growth. Technological advances in IC materials and design have produced generations of ICs where each generation has smaller and more complex circuits than the previous generation. In the course of IC evolution, functional density (i.e., the number of interconnected devices per chip area) has generally increased while geometry size (i.e., the smallest component (or line) that can be created using a fabrication process) has decreased. This scaling down process generally provides benefits by increasing production efficiency and lowering associated costs. Such scaling down has also increased the complexity of processing and manufacturing ICs and, for these advances to be realized, similar developments in IC processing and manufacturing are needed.
For example, the need to perform higher resolution lithography processes grows. One method of many lithography techniques to improve resolution is to use a super binary mask (BIM) or a phase shift mask (PSM). A phase shift masks typically include an alternative phase shift mask (alt. PSM), and an attenuated phase shift mask (att. PSM). Disadvantages of using a phase shift mask are haze defects and haze related crystal growth defects on the photomask. Haze defects and haze related crystal growth defects on a photomask are photo-induced defects during high energy expose, wave length ranging from 450 nm to 13 nm, such as 248 nm deep ultraviolet (DUV) lithography process or 13 nm extreme ultraviolet (EUV) lithography process. The haze defects often require repeated chemical cleaning processes to increase the IC production cycle time and cost. It is desired to have improvements for photomask haze defects reduction.